Entry 1 sense Webster, 1913 Halysites /(hăl`ĭ*sī"tēz)/ · Hal·y·si·tes · IPA 01 n. A genus of Silurian fossil corals; the chain corals. See Chain coral, under Chain. 1. A genus of Silurian fossil corals; the chain corals. See Chain coral, under Chain.(Paleon.) See: Chain